721i 



PHYSIOLOGY OF THE NERVOUS SYSTEM. 



hip are those primarily irritated : there is no 

 connection at the periphery between these 

 nerves and those of the knee ; both, however, 

 are of spinal origin, and must be implanted 

 near to each other in the spinal cord. This, 

 then, is the only situation at which any com- 

 munication may be established between them, 

 and it is probable that that communication 

 takes place through the vesicular matter in 

 which both are implanted. The irritation from 

 the hip, then, extends to the cord ; it is there 

 propagated to the vesicular matter in which 

 the nerves of the knee are implanted : in other 

 words, it is reflected to them, and thus pain is 

 referred to the peripheral extremity of those 

 nerves, in conformity with the known law of 

 sensitive nerves, and in this way the pain is 

 felt in the knee. A similar explanation applies 

 to the other cases referred to. 



There is no other mode of explaining these 

 phenomena consistently with the known dispo- 

 sition and properties of nerve-fibres; and as 

 experiment demonstrates the reflecting power 

 of the cord from sensitive to motor, we are 

 justified in referring these phenomena to a simi- 

 lar reflecting power from sensitive to sensitive 

 nerves. We shall see further on that other 

 nervous centres possess the same power. 



The functions of the body with which the 

 spinal cord is immediately concerned are the 

 following: 1. The voluntary movements and 

 sensations of the trunk and extremities, and of 

 the viscera contained in the thorax, abdomen, 

 and pelvis. For these, however, the integrity 

 of its connection with the brain is necessary. 

 2. The physical actions, or, in other words, the 

 involuntary movements of the trunk and extre- 

 mities. 3. The actions necessary for locomotion, 

 which are a combination of mental and physical 

 nervous actions. 4. The physical actions of 

 some of the internal organs. These are the heart, 

 the intestinal canal, the bladder, and the genera- 

 tive organs, both male and female. The influence 

 of the spinal cord over all these organs is, how- 

 ever, very limited, and inasmuch as they have a 

 considerable degree of inherent muscular power, 

 as well as receive nerves connected with other 

 centres, namely, the sympathetic ganglia, they 

 are in a great degree independent of the cord. 



Dr. M. Hall's doctrines. Using the term 

 spinal cord to designate a centre or axis of 

 physical nervous actions (the true spinal cord), 

 provoked by ''excitor" nerves of the head, 

 neck, trunk, and extremities, and of parts con- 

 nected with them, Dr. Marshall Hall assigns to 

 it very extended functions. 



" Every act of ingestion, of retention, of 

 expulsion, or of exclusion," says this physiolo- 

 gist,* " is a reflex act; an excito-motor act, an 

 act of the true spinal system, performed through 

 its incident nerves, its central organ (the true 

 spinal marrow), and its reflex motor nerves; 

 an act of the special power seated in this sys- 

 tem." ***** If we wish, then, 

 to know what are the special acts of the true 

 spinal system, we have only to ask what are 

 the acts by means of which masses of matter 



* New Memoir on the Nervous System, 1843, 

 p. 51, 191-192. 



are ingurgitated into and expelled from the 

 animal economy." And in a table which fol- 

 lows these paragraphs, and which is intended 

 to display at one view the physiology of the 

 true spinal system (so calledj, he refers to this 

 source, I. The excited actions: 1, of the iris 

 and eyelids ; 2, of the orifices the larynx and 

 the pharynx ; 3, of the ingestion (1, of the food, 

 as in suction and in deglutition; 2, of the air 

 in respiration; 3, of the semen or conception); 

 4, of exclusion ; 5, of the expulsion or of eges- 

 tion ( 1 , of the feces ; 2, of the urine ; 3, of the 

 perspiration ; 4, of the semen ; 5, of the foetus 

 or parturition) ; 6, of the sphincters (1, of the 

 cardia ; 2, the valvula Coli ? (sic) ; 3, the 

 sphincter ani ; 4, the sphincter vesicae). II. 

 The direct action or influence: 1, in the tone; 

 and 2, in the irritability of the muscular 

 system.* 



I shall content myself here with pointing out 

 how slight are the grounds upon which so large 

 a function is assigned to the spinal system, and 

 so exclusive a view is taken of the various ac- 

 tions which are affirmed to be under its control. 

 Further on I hope to show that the hypothesis 

 of a special centre (the true spinal narrow) with 

 its incident and reflex nerves is inadequate to 

 the explanation of the phenomena of the ner- 

 vous system. 



A careful analysis of the various acts of in- 

 geslion, &c. will show that they cannot be 

 regarded entirely as reflex acts. Thus the in- 

 gestion of food is effected by prehension, which 

 is voluntary, by suction, as in the young, which 

 is partly voluntary and partly reflex, and by 

 deglutition. Now this last act is partly volun- 

 tary, as in the mouth ; when the food has been 

 brought within the grasp of the fauces it is 

 reflex, and that portion of the act which takes 

 place in the oesophagus is partly reflex and 

 partly due to the influence of the stimulus of 

 distension upon the muscular coat. The most 

 purely physical portion of the act of deglutition 

 is that which takes place in the vicinity of the 

 rima glottidis, which, if not regulated by very 

 exact physical changes, and if not, in a great 

 degree at least, independent of mind, might 

 frequently endanger the life of the individual 

 by the deviation of the morsel of food from its 

 proper course, so as to plug up or encroach 

 upon the orifice which leads to the respiratory 

 organs. f 



The act of respiration is undoubtedly essen- 

 tially reflex, but it is likewise very much under 

 the control of the will, and may at any time be 

 increased or diminished in frequency under the 

 influence of either volition or emotion. 



In conception, or what Dr. Hall calls the 

 ingestion of semen, I am at a loss to conceive 

 what reflex act can occur. The grasping of 

 the ovary by the extremity of the Fallopian tube 

 is more likely to be an act of emotion due to 

 the general sexual excitement than a reflex phe- 

 nomenon excited by the stimulus of coition. 

 And as to the ingestion of the seminal fluid, that 



* Lnc. cit. p. 52. 



t Here we notice the operation of the law of our 

 preservation, which, according to Prochaska, regu- 

 lates these reflex acts. 



